Variable inductance



April 14,1925.

C. LlEDEL VARIABLE INDUCTANCE Filed March 24,

ATTORNEY WITNESS:

Patented Apr. 14, 1925.

CLARENCE LIEDEI), MAYBEE, MICHIGAN.

VARIABLE mnuc'rimcn.

Application filed March 24, 1923. Serial N 0. 627,414.

To all whom it may concemm Be it known that I, CLARENCE LIEDEL, a citizen of the United States, residing at Maybee, in the county of Monroe and State of Michigan, have invented new and useful Improvements in Variable Inductance, of which the following is a specification.

This invention relates to radio receiving apparatus, particularly that type employing a crystal detector, and has for its object the provision of a novel compact apparatus ineluding a peculiarly constructed and delicatcly variable inductance by means of which delicate adjustment may be made to secure great sensitiveness and selectivity.

Another object is the provision of an apparatus of this character in which the core upon which the inductance is wound serves to enclose the detector and various binding posts so that the entire device will occupy the minimum space and whereby the crystal detector will be protected against being accidentally touched and thrown out of adjustment.

An additional object is the provision of an apparatus of this character which will be very simple andinexpensive to manufacture, easy to control and operate, efiicient in service, and a general improvement in the art.

With the above and other objects and advantages in view, the invention consists in the details of construction to be hereinafter more fully described and claimed and-illustrated in the accompanying drawings in which- Figure 1 is a side elevation of the device.

Figure 2 is a top plan view thereof.,

Figure 3 is a cross sectional view on the line 33 of Figure 2.

Referring more particularly to the drawings, I have shown the body of my device as consisting of a cylindrical form or core 10 having a circular bottom 11. This core may be formed of card-board, bakelite, formica, fiber, or any other insulating matcriaL. The upper edge of this core is referabl formed with an overhanging ange 12 w ich serves to retain in place and also to protect a coil 13 of enameled wire of suitable gage wound spirally u on the core and havmg its outermost sur ace scraped free from insulation. The lower terminal 14 of this winding is connected with a binding post 15 which rises from the bottom 11 and which is designed for connection of the aerial lead-in therewith. Also mounted upon the bottom in spaced relation to the binding post 15 is a second binding post 16 which is for one terminal of the phones and which is connected with: the'binding' post 14 with a wire 17. The upper terminal of the winding 13 is simply passed through a plurality of holes in the core or otherwise secured, as indicated at 18, whereby to be permanent or unconnected with any of the mechanism.

Disposed upon the bottom 11 is an elongated metallic strip 19 which has one end pivoted by a binding post 20 which rises from the base, and pivoted for rotatable movement upon the free end of this strip is a metal cup 20 which contains the crystal 21. This cup may be mounted upon the strip by means of a rivet 22 or. other equiva lent means.

The numeral 23 designates an angular .metal strip which has one end ofiset downwardly to provide a bearing foot 24 pivoted on the base 11 by a binding post 25. The free end of this angular strip carries an adjusting screw 26 upon which is mounted a cat-whisker 27 designed for engagement with the crystal. Intermediate its ends the strip 23 has threaded therethrough an adj ust-.

ing screw 28 which has its free end bearing. 1

upon a metal plate 29 secured upon the bottom and formed at its edges with an upstanding lip or flange 30 which will prevent the free end of the screw 28 .from slipping ofi" of the plate. r

The binding post 25 isadapted forconnection with the other terminal of the phones and the binding post 20 is adapted for connection with the ground wire. Connected with the binding post 20 is a section of flexible conducting cord or wire 31 which has its free end carrying a contact clip 32 which straddles the form with the free end of one arm 32 bearing against the inside of the core and the free end of the other arm 34: formed with a lip 35 contacting with the coil 13. vThe connection of the wire 31 with the clip 32 might of course be made in difierent ways but it is really preferable that the wire be connected with a post or stem 36 which is swivelly connected with the clip so as to prevent twisting and kinking of the wire or breaking when the clip is moved to different. positions along the circ nnference of the coil.

The diagram of connection, or the hookup is shown in the detail views in which it will be observed that the aerial A is connected with the binding post 15, the ground wire G is connected with the hinding post 20 and the terminals of the phones P are connected wit the binding posts 16 and 25.

1n the operation of the device tuning is effected by sliding the clip transversely of the coil 13 for obtaining the rough adjustment and then hy moving the clip circuinierentially of the individual convolution engaged by it so as to make a delicate adjustment or the inductance in the circuit. Owing to the fact that the wire 13 is wound spirally upon the core it is apparent that by sliding he clip circuniterentially of the core it may be progressed from. one convolution to the neat without utilizing its slidable function and owing to this peculiar arrangement it is obvious that a pin point adjustment may be made so as to obtain the greatest sensitiveness and selectivity. The current enterin the binding post 14: from the aerial, divides, one portion passing through wire 14:, coil 13, clip 32, wire 31, and binding post 20 to the ground, and the other portion passing through the phones P, binding post 25, strip 23, screw 26, catwhisker 21, strip 19, and binding post 20, to the ground. In actual practice I have discovered that this circuit is very efi'ective and sensitive and selective. Mechanically, adjustment to obtain a sensitive spot on the crystal is easily made owing to the pivotal mounting of the strip 19, the revolubility of the cup 20, and the adjustahility of the cat-whisker holding screw 26, together with the adjustment of tension by means of the screw 28. It is to be seen that practically every conceivable adjustment of the detector is provided for so that the set will operate with the maximum eficiency and with the utmost ease.

. 'While 1 have shown and described the preferred embodiment of my invention, it is of course to be understood that I reserve the right to make such changes in the form,

construction and arrangement of parts as will not depart from the spirit of the invention or the scope of the subjoined claims.

- -What is claimed is:

1. In a radio receiving apparatus, an inductance consisting of a cylindrical core having enameled wire wound thereon spirally, the outermost surfaces of the successive convolutions being freed from insulation, and a slide contact consisting of a clip straddling the edge of the core and slidable transversely and circumierentially of said convolutions.

2. In a radio receiving apparatus, an inductance consisting of a cylindrical core havin enameled wire wound there-on spirally, the outermost surfaces of the succcssive convolutions being free from insulation, and a slide contact consisting of a clip straddling the edge oi the core and slidable transversely and circunit'erentially of said convolutions, a conducting wire, and a connecting stenrconnected with said wire and sWiv-elly connected with said clip.

3. In a device of the character described, a cylindrical hollow core ,having a closed bottom for supporting auxiliary apparatus, said core losing provided at its upper edge with an outwardly extending retaining flange, wire wound spirally upon the core and having its successive convolutions insulated one from another with the outer surfaces of the convolutions freed from insulation, a Ll-shaped clip engaged upon the wall of the core and slidable upon said flange, one arm of the clip having its free end formed with an inward extension of ll-shape having its vertex slidably engageahle with said wire, the clip being movable transversely of all the convolutions or circuinterontially thereof, and a take off connection swivelly connected with the bight portion of the clip, said flange being engageable by said extension for preventing removal of the clip from the core.

in testimony whereof I afit my signature.

CLARENCE LIEDEL. 

